Generally, an insert is coupled to a cutting tool mounted on a machine tool, and used for cutting a workpiece composed of ferrous, nonferrous metal, nonmetal materials, and so on.
Such insert typically includes an upper surface, a lower surface, and a plurality of side surfaces connecting the upper surface with the lower surface. An upper cutting edge is provided between the side surface and the upper surface, and a lower cutting edge is provided between the side surface and the lower surface.
One of conventional examples is disclosed in Korean Pat. No. 10-1240880 and illustrated in FIGS. 7 and 8, which is a double sided insert including an upper side (upper surface) 11, a lower side (upper surface) 12, and cutting edges 13A, 13B, 14A, 14B, 15A, 15B formed therebetween, in which the upper side 11 and the lower side 12 are substantially identical such that a use of dual sides is enabled. Specifically, in order to cut the workpiece with more ease, a main cutting edge (hereinbelow, ‘main cutting edge’) 16 is provided with an inclination angle, and such main cutting edge 16 is connected to a chip break concave portion 21 (hereinbelow, ‘inclined surface’) concaved with respect to plane surfaces P1, P2.
However, because the related double sided insert is a dual-surface type insert that uses both the upper surface 11 and the lower surface 12, the insert has a limited thickness and therefore, the main cutting edges on both of the surfaces have limited inclination angle. In order to overcome such limit, the thickness of the insert can be increased, but in that case, it is difficult to fabricate a tool holder, and coupling characteristic also deteriorates. If the main cutting edge is fabricated to be approximately half the size of one side surface, this rather causes deteriorated cutting efficiency because the cutting depth is decreased.